Rubber crawlers include friction-driven rubber crawlers, in which an outer circumferential face of a drive wheel on a vehicle body side is placed in contact with an inner peripheral face of a rubber crawler, and drive force is transmitted from the drive wheel to the rubber crawler by frictional force between the two. In this type of rubber crawler, rubber projections for guiding wheels, including the drive wheel, idle wheels, and rollers, are provided at specific intervals along the inner peripheral face of the rubber crawler.
In the rubber projections, there is a tendency toward increasing the projection length in the crawler peripheral direction, the projection width in the crawler width direction, and the projection height from the inner peripheral face of the crawler, from the perspectives of suppressing wear due to contact with the wheels, and preventing disengagement from the wheels.
When the size of the rubber projections is increased, the last points to be vulcanized (where the cumulative amount of heat from the mold is smallest) during vulcanization of the rubber crawler are deep within the rubber projections. In order to realize specific material properties of the rubber in the rubber crawler, vulcanization needs to continue until the last points to be vulcanized have undergone a specific degree of vulcanization. However, there is also a need to perform vulcanization at low temperature in order to avoid over-curing the rubber. The vulcanization time increases as a result.
A rubber crawler described in Japanese Patent Application Laid-Open (JP-A) No. 2004-330830 achieves a reduction in vulcanization time by disposing a composite layer containing metal fibers inside a rubber projection to raise the thermal conductivity of the rubber projection.